Issue #13959: Have

importlib.abc.FileLoader.load_module()/get_filename() and
importlib.machinery.ExtensionFileLoader.load_module() have their
single argument be optional as the loader's constructor has all the
ncessary information.

This allows for the deprecation of
imp.load_source()/load_compile()/load_package().

Lib/importlib/test/extension/test_loader.py

@@ -1,4 +1,4 @@
-from importlib import _bootstrap
+from importlib import machinery
 from . import util as ext_util
 from .. import abc
 from .. import util
@@ -11,10 +11,20 @@ class LoaderTests(abc.LoaderTests):
 
     """Test load_module() for extension modules."""
 
+    def setUp(self):
+        self.loader = machinery.ExtensionFileLoader(ext_util.NAME,
+                                                     ext_util.FILEPATH)
+
     def load_module(self, fullname):
-        loader = _bootstrap.ExtensionFileLoader(ext_util.NAME,
-                                                ext_util.FILEPATH)
-        return loader.load_module(fullname)
+        return self.loader.load_module(fullname)
+
+    def test_load_module_API(self):
+        # Test the default argument for load_module().
+        self.loader.load_module()
+        self.loader.load_module(None)
+        with self.assertRaises(ImportError):
+            self.load_module('XXX')
+
 
     def test_module(self):
         with util.uncache(ext_util.NAME):
@@ -25,7 +35,7 @@ class LoaderTests(abc.LoaderTests):
                 self.assertEqual(getattr(module, attr), value)
             self.assertTrue(ext_util.NAME in sys.modules)
             self.assertTrue(isinstance(module.__loader__,
-                                    _bootstrap.ExtensionFileLoader))
+                                    machinery.ExtensionFileLoader))
 
     def test_package(self):
         # Extensions are not found in packages.

Lib/importlib/test/source/test_file_loader.py

@@ -1,5 +1,6 @@
 from ... import _bootstrap
 import importlib
+import importlib.abc
 from .. import abc
 from .. import util
 from . import util as source_util
@@ -24,6 +25,40 @@ class SimpleTest(unittest.TestCase):
 
     """
 
+    def test_load_module_API(self):
+        # If fullname is not specified that assume self.name is desired.
+        class TesterMixin(importlib.abc.Loader):
+            def load_module(self, fullname): return fullname
+
+        class Tester(importlib.abc.FileLoader, TesterMixin):
+            def get_code(self, _): pass
+            def get_source(self, _): pass
+            def is_package(self, _): pass
+
+        name = 'mod_name'
+        loader = Tester(name, 'some_path')
+        self.assertEqual(name, loader.load_module())
+        self.assertEqual(name, loader.load_module(None))
+        self.assertEqual(name, loader.load_module(name))
+        with self.assertRaises(ImportError):
+            loader.load_module(loader.name + 'XXX')
+
+    def test_get_filename_API(self):
+        # If fullname is not set then assume self.path is desired.
+        class Tester(importlib.abc.FileLoader):
+            def get_code(self, _): pass
+            def get_source(self, _): pass
+            def is_package(self, _): pass
+
+        path = 'some_path'
+        name = 'some_name'
+        loader = Tester(name, path)
+        self.assertEqual(path, loader.get_filename(name))
+        self.assertEqual(path, loader.get_filename())
+        self.assertEqual(path, loader.get_filename(None))
+        with self.assertRaises(ImportError):
+            loader.get_filename(name + 'XXX')
+
     # [basic]
     def test_module(self):
         with source_util.create_modules('_temp') as mapping: